This invention is related to apparatus for continuously mixing materials of different types. More specifically, it relates to mixing apparatus for the continuous preparation of liquid or liquid containing mixtures by (i) continuously loading a casing with fluid materials of different types, e.g., different liquids or a powder and a liquid; (ii) continuously mixing the materials by means of an upper bladed disk turbine impeller and a lower bladed disk turbine impeller which rotate individually with respect to each other to prepare a coarse mixture; and (iii) continuously feeding a liquid into the casing for mixing with the coarse mixture.
Japanese Patent Application Publication 2000-449 describes a process for preparing a water based grease like organopolysiloxane liquid by loading a mixing chamber with a liquid organopolysiloxane, an emulsification agent, and water, and mixing the components with a rotating disk equipped with scrapers. A disadvantage of this process consists in low stability and in coarsening of the grains contained in the emulsion. These problems occur because from the beginning of the process, the emulsification is conducted in a diluted state.
U.S. Pat. No. 4691867 (Sep. 8, 1987) describes a continuous mixer for the preparation of a slurry from a fine powder, oil coke, or similar pulverized bodies. The pulverized bodies and a liquid are fed into an upper mixing chamber and mixed in a humidified state by a rotating upper mixing disk. The resulting coarse mixture is sent to a lower mixing chamber where it is converted to a slurry by a rotating lower mixing disk. As coarse mixture flows to the lower mixing chamber with pulsation, the mixture contained in the lower mixing chamber tends to flow back to the upper mixing chamber. As a result, as the pulverized bodies and liquid are loaded into the upper mixing chamber, there is no means to use the mixtures other than in a diluted state. This is not acceptable in order to provide dispersions of the pulverized bodies.
U.S. Pat. No. 5599102 (Feb. 4, 1997) discloses a mixing apparatus for the continuous preparation of low viscosity mixtures by (i) loading a mixing chamber with a powdered material and a liquid, (ii) preparing a coarse mixture with a rotating disk, (iii) supplying another portion of the liquid to the rotating disk, and (iv) mixing it with the coarse mixture. A disadvantage of this mixing apparatus is in preparing emulsions. Thus, as the second portion of the liquid comes closer to the level of the rotating disk, the grain size of the particles become too large, and as a result, the mixture becomes unstable. When using this type of device to mix a powder with a liquid, the resulting mixture has too high a viscosity.
Therefore, it is an object of the invention to provide a continuous mixing apparatus for mixing materials of different types which is capable of preparing mixtures of high stability, quickly, uniformly, without an increase in the level of the liquid, with low viscosity and low density of the mixture. These and other features of the invention will become apparent from a consideration of the detailed description.